Auto merge of #2035 - Turbo87:fetch-adapter, r=locks

Remove obsolete `FetchAdapter` mixin

`ember-data` will use it `fetch()` automatically now (see emberjs/data#6082)

Resolves #1995

r? @locks

Author: bors

app/adapters/application.js

@@ -1,6 +1,5 @@
 import DS from 'ember-data';
-import AdapterFetch from 'ember-fetch/mixins/adapter-fetch';
 
-export default DS.RESTAdapter.extend(AdapterFetch, {
+export default DS.RESTAdapter.extend({
   namespace: 'api/v1',
 });